Welcome to the forum! There are a couple of things... The ones I've seen advertized were for the 75B and the SP-01. I'm not sure if there are any differences. I could try mine, but I'm not home. I haven't checked them side by side, but the 75B does seem (if I remember correctly) a little different than the SP-01. Until someone with more knowledge chimes in, don't force it and perhaps the best thing to do would be to call the vendor tomorrow. You couldn't do it wrong, I don't think, as long as you are putting stuff in the same way it came out, which I'm sure you are doing...
OK. Just checked. The SP-01 rod will NOT fit in the 75B, but the 75B will fit in the SP-01. This may not have anything to do with your problem, but I figure it's good to eliminate some variables. A guide rod in a CZ 75-based pistol (everything from the 75B to the P/SP-01/06/07) is easy as pie. If it's not working, I have to wonder if whoever you bought it from sent you the wrong piece for the wrong pistol. If you look in our 75B sub-forum, you should find some more info that might be helpful.
And finally, once you get it sorted I would love to hear your impressions. There's been some discussion here lately as to whether or not the rod is helpful or detrimental to the overall health of our firearms.
Again, Welcome to CZ Forum! We're happy to have you here!